AU624965B2

AU624965B2 - Process for improving the fluidity of mineral oils and mineral oil distillates

Info

Publication number: AU624965B2
Application number: AU57910/90A
Authority: AU
Inventors: Wolfgang Dr. Payer; Werner Dr. Reimann
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1989-06-29
Filing date: 1990-06-28
Publication date: 1992-06-25
Anticipated expiration: 2010-06-28
Also published as: CA2020104A1; ATE82587T1; ES2054152T3; KR930011928B1; DE59000480D1; DE3921279A1; ZA904894B; AU5791090A; KR910001004A; JPH0339385A; EP0405270A1; JPH0768505B2; EP0405270B1

Abstract

The flow properties of mineral oils and mineral oil distillates are improved by addition of a mixture of an ethylene/vinyl acetate copolymer and an ethylene/vinyl acetate/N-vinylpyrrolidone terpolymer.

Description

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.4 Form COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-69 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art p Name of Applicant Address of Applicant Actual Inventor Address for Service HOECHST AKTIENGESELLSCHAFT 50 Bruningstrasse, D-6230 Frankfurt/Main 80, vederal Republic of Germany WOLFGANG PAYER and WERNER REIMANN WATERMARK PATENT TRADEMARK ATTORNEYS.

LOCKED BAG NO. 5, HAWTHORN, VICTORIA 3122, AUSTRALIA Complete Specification for the invention entitled: PROCESS FOR IMPROVING THE FLUIDITY OF MIN r<AL OILS AND MINERAL OIL

DISTILLATES

The following statement is a full description of this Invention, including the best method of performing it known to us Us f 1 1 L -clc~~ 1 Process for improving the fluidity of mineral oils and mineral oil distillates The present invention relates to a process for improving the fluidity of mineral oils and mineral oil distillates by the addition of mixtures of ethylene/vinyl acetate copolymers and ethylene/vinyl acetate/N-vinylpyrrolidone terpolymers.

Depending on the provenance, mineral oils and mineral oil distillates contain varying quanti ies of dissolved paraffin, which precipitates at low temperatures in the form of plate-like crystals, in which oil is still o' o occluded. This considerably impairs the fluidity of mineral oils and mineral oil distillates. For example in the case of diesel fuel, this leads to a blockage of 15 filters, with the consequence that the fuel supply to the combustion units, such as internal-combustion engines or So° jet engines, takes place irregularly or is completely interrupted. Likewise, faults can arise in the transport of fuel oils in combustion plants, if such wax precipitations occur due to low temperatures.

The transport of middle distillates through pipelines over relatively long distances can be impaired in winter by the precipitation of paraffin crystals.

s t i, In order to control the precipitation of paraffin wax, additives are added to the mineral oils and mineral oil distillates, in particular to the so-called middle distillates, which additives modify the size and shape of paraffin crystals, so that the middle distillates remain fluid even at low temperatures. The economically most important pour point depressants and flow improvers for mineral oils and mineral oil distillates are copolymers of ethylene with esters of vinyl alcohol, in particular with vinyl acetate. Such copolymers and their use are described, for example, in DE-C 1,914,756 and DE-A 2,515,805. From Published Japanese Patent Application i 2 58 80,386, abstracted in C.A. 99 (1983), 215519, it is known to use terpolymers of ethylene, vinyl acetate and N-vinyl-2-pyrrolidone as flow improvers.

In practice it has been found that the effectiveness of these copolymers as flow improvers depends on the properties of the mineral oils and mineral oil distillates, whose fluidity is to be increased. In the case of middle distillates, for example, it is affected, inter alia, by the total n-paraffin content and the content of n-paraffins of certain chain lengths. The content and distribution of paraffin are determined by the proportions of light, medium-heavy and heavy distillate fractions, of which the middle distillate is composed, and by the crude oil provenance.

It is therefore understandable that the ethylene/vinyl acetate copolymers, in spite of their excellent suitability for increasing the fluidity, do not always show the desired effect. In such cases, the problem is then overcome by adding them in large quantities or by mixing the mineral oil or the mineral oil distillate with 'O low-boiling hydrocarbons.

Another possibility of increasing the effectiveness of flow improvers is to use additive combinations. Thus, in DE-A-2,639,672, mixtures of polymers with ethylene backbone and copolymers of Cz- to Cs-olefins are described, which can lead to a synergistic imp Dvement of the flow properties of distillate hydrocarbon oils in the Scold.

According to US-A 3,660,057, mixtures of an ethylene/vinyl acetate copolymer and a solid hydrocarbon, which is free of n-paraffins, are used as flow improvers.

Mixtures- which are composed of an ethylene-containing polymer, beeswax, ozocerite and/or a long-chain alphaolefin, are disclosed in US-A-4,019,878 as flow improvers

I

1 3 for crude oil middle distillates.

Even though the known substances and substance mixtures have, in many cases, improve and sometimes even greatly improved the fluidity of mineral oils and mineral oil distillates of various provenances and compositions at low temperatures, there is nevertheless a lack of additives having as versatile as possible an applicability, or universal applicability in the ideal case.

It was therefore the object to provide additives which have an even wider range of application as compared with S' the known flow improvers. They should increase the fluidity of even those oils with which the known additives show only a slight effect or none at all.

0 0 S 15 20 The invention represents a process for improving the fluidity of mineral oils and mineral oil distillates. It comprises adding mixtures of an ethylene/vinyl acetate copolymer and an ethylene/vinyl acetate/N-vinylpyrrolidone terpolymer to the mineral oils or mineral oil distillates.

Surprisingly, it has been found that the process according to the invention effectively suppresses the precipitation of paraffins from mineral oils and mineral oil distillates and holds paraffin crystals, which may o 0 S. 25 have precipitated, in suspension. The additives used o"o 0 according to the novel process thus counteract a rise in the viscosity of the hydrocarbon mixtures at falling temperatures and lower the pour point, The claimed procedure has proved suitable for improving the fluidity of mineral oils and distillation products thereof, independently of their qualitative and quantitative composition. It is of particular importance that the two components boost each other synergistically. The effectiveness of the polymer mixture is thus greater than the sum of the effectiveness of its constituents.

-1 I~ 4 The ethylene/vinyl acetate copolymers used according to the invention contain 20 to 40 by weight of vinyl acetate. Copolymers with 25 to 35 by weight of vinyl acetate have proved particularly suitable. 'Teir viscosity measured in accordance with German Standard DIN 53 019 in a rotary viscometer (made by Haake) at 140°C, to 1000 mPa.s, especially 30 to 250 mPa.s.

Per 100 CH, groups they contain 1 to 10 and preferably 2 to 7 CH 3 groups, not originating from the acetate radical of the vinyl acetate, in the side chains. The determination of the number of CH3 groups is here carried out by H-NMR spectroscopy.

The preparation of the ethylene/vinyl acetate copolymers ,1 ,is known. It can be carried out, for example, by polymerization of the monomer mixture at pressures from 5 to MPa and at temperature.s from 70 to 150°C in the presence of initiators forming free radicals. The reaction medium used can be an organic solvent or suspending agent such as toluene.

20 The ethylene/vinyl acetate/N-.vinylpyrrolidone terpolymers used as the second constituent of the flow improver mixture contain 15 to 50 by weight, in particular 20 to by weight, of vinyl acetate and 0.5 to 10 by weight, in particular 1.0 to 5.0 by weight, of N-vinylpyrrolidone. Their viscosity, measured in the same way as in the case of the ethylene/vinyl acetate copolymers, is 100 to 5000 mPa.s and especially 150 to 1500 mPa.s.

The production of ethylene/vinyl acetate/N-vinylpyrrolidone terpolymers is known. It is carried out, for example, by polymerization of the monomer mixture at pressures above 5 MPa and temperatures above 60°C in the presence of initiators', forming free radicals, in autoclaves. Organic solvents which dissolve 5 by weight of ethylene are used as the reaction medium. Methanol, t-butanl, benzene and dioxane are suitable (cf. FR t-butanol, benzene and dioxane are suitable (cf. FR Vr O« -A I~ T 5 1,392,354).

The weight ratio of the two polymers in the additive mixture can be varied within wide limits. It has proved suitable to use the ethylene/vinyl acetate copolymer and ethylene/vinyl acetate/N-vinylpyrrolidone terpolymer in a weight ratio from 1:1 to 100:1. Mixtures which contain copolymer and terpolymer in a weight ratio from 3 1 to 1 are preferred.

The process according to the invention improves the fluidity of both mineral oils and mineral oil distillates. The term mineral oils is here to be understood as S°o° meaning especially crude oils and distillation residues, such as heavy fuel oil. Hydrocarbon fractions having a boiling point between about 150 and 400°C are designated as mineral oil distillates. These include, for example, petroleum, light fuel oils and diesel fuels. The middle distillates such as fuel oil EL and diesel oil are of particular importance.

The mixture of the two polymers is added to the mineral oils or mineral oil distillates in the form of solutions which contain 20 to 70 by weight, relative to the solution, of the polymers. Suitable solvents are aliphatic or aromatic hydrocarbons or hydrocarbon mixtures, for example naphtha fractions. Kerosene is particularly suitable. The quantity of polymer, relative to mineral o° oil or mineral oil fractions, should amount to 0.001 to 2 and preferably 0.005 to 0.5 by weight.

The polymer mixtures can be used alone or also together with other additives, for example with other power point depressants or dewaxing auxiliaries, with corrosion inhibitors, antioxidants, sludge inhibitors and additives for lowering the cloud point.

The process according to the invention is explained in more detail by the examples which follow.

6 Examples 1 to 4 relate to the process according to the invention. Examples 5 to 7 reproduce the results of comparative tests, which are obtained with the use of ethylene/vinyl acetate copolymers alone (Examples 5 and 6) and of an ethylene/vinyl acetate/N-vinylpyrrolidone terpolymer alone (Example 7).

The effectiveness of the fluidity improvement processes investigated is described by reference to the "cold filter plugging test" (CFPP test). The test is carried out in accordance with DIN 51 428. It has also been published in J. of the Inst. of Petr., Vol. 52, June 1966, pages 173 to 185.

.oo. Three middle distillates, Ml, M2 and M3, were used for o 1 testing. They are characterized by the property data compiled in table 1.

o Examples 1 to 8: In the examples which follow, the polymers characterized below are used alone or as a mixture.

A: An ethylene/vinyl acetate cop., i- having a vinyl acetate content of 30.5 by weight and a viscosity of 30 mPa.s at 140 0

C.

B: An ethylene vinyl/acetate copolymer having a vinyl acetate content of 29.8 by weight and a viscosity of 80 mPa.s at 140"C.

C: An ethylene/vinyl acetate/N-vinylpyrrolidone terpolymer having a vinyl acetate content of 23.2 by weight and an N-vinylpyrrolidone content of 1.4 by weight and a viscosity of 230 mPa.s at 140 0

C.

The vinyl acetate content of the polymers is determined by the pyrolysis method. For this purpose, 200 mg of the polymer are heated with 300 mg of pure polyethylene in a

J

7 pyrolysis flask for 5 minutes at 450 0 C and the cracking gases are collected in a round-bottomed 250 ml flask. The acetic acid formed is reacted with an NaI/KIO 3 solution and the iodine released is titrated with Na 2 S20 3 solution.

The N-vinylpyrrolidone content in the polymer is calculated from the nitrogen content of the polymer, determined by the Dumas method.

Table 2 contains data on the effectiveness of the process according to the invention for improving the fluidity of mineral oils and mineral oil distillates.

o o o 0 i L t4 0 6 1

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8- Table 1: Characteristics of tbe test oils Cloud point 0

C)

(according to DIN 51 597) +1 -2.2 +3 CFPP (CC) -5 -4 -2 Pour pint -6 -15 -9 Wax appearance t~~aue("C) 0 -6.0 n-Paraf fin content ()41 37 Boiling analysis 0

C)

Initial boiling point 176 184 190 217 234 90 350 350 Final boiing point 381 377 373 0 o e 0 0 0 o -4 0 40 0 0 0 000~ 0 a ta 0 00 0 720 9- Table 2: Effectiveness of the polyumer mixtures Ex- Carposition Concem- LawP (C) aiaple (parts by wt.) tration. M 1 1M2 M43 1 85 A+ 19C 0 5 4 2 8 -11 100 -17 125 -17 200 -14 250 2 95 B 5 C 0 -5 2 -9 -17 100 I-18 125 -16 200 -14 250 -17 3 910 B +10 C 0 5 4 2 9 9 75 -17 100 -18 125 -17 200 -12 250 -17 485 B +15C 0 5 4 2 9 -13 75 -16 100 -18 125 -18 200 -12 250 -17 0 60 6 4 4 44 C 6 44 4 10 Table 2: Continued 4 4 4 4 4 4 4 5 4 44

Claims

1. A process for improving the fluiuity of mineral oils and mineral oil distillates, which comprises adding mixtures of an ethylene/vinyl acetate copolymer and an ethylene/vinyl acetate/N-vinylpyrrolidone terpolymer to me mineral oils or mineral oil distillates.

2. The process as claimed in claim 1, wherein the ethylene/vinyl acetate copolymer contains 20 to 40 by weight of vinyl acetate, has a viscosity measured at 1400C from to 1000 mPa.s, aid contains, per 100 CH 2 groups, 1 to 10 CH 2 groups not originating from the acetate radical of the vinyl acetate, in the side chains.

3. The procn~s as claimed in claim 2, whereas the ethylene/vinyl acetate copolymer contains 25 to 35 by weight of vinyl acetate, has a viscosity measured at 1400C from 0000 30 to 250 mPa.s and contains, per 100 CH 2 groups 2 to 7 CH 3 groups not originating from the acetate radical of the vinyl acetate. 0 0 Qo 0

4. The process as claimed in claim 1, wherein the ethylene/vinyl acetate/N- vinylpyrrolidone terpolymer contains 15 to 50 by weight of vinyl acetate and 0.5 to by weight of N-vinylpyrrolidone and has a viscosity measured at 140°C from 100 to 5000 mPa.s.

The process as claimed in claim 4, wherein the ethylene/vinyl acetate/N- vinylpyrrolidone terpolymer contains 20 to 35 by weight of vinyl acetate and 1.0 to by weight of N-vinylpyrrolidone and has a viscosity measured at 140°C from 150 to 1500 mPa.s.

6. The process as claimed in claim 1, wherein the ethylene/vinyl acetate copolymer and ethylene/vinyl acetate/N-vinylpyrrolidone terpolymer are used in a weight ratio from 1:1 to 100:1.

7. The process as claimed in claim 1, wherein the ethylene/vinyl acetate copolymer and ethylene/vinyl acetate/N-vnylpyrrolidone terpolymer are used in a weight ratio trom 3:1 to 20:1. 1I 12

8. A mineral oil or mineral oil distillate of improved flow behaviour, which contains 0.001 to 2 by weight of a mixture of an ethylene/vi;'yl acetate copolymer and an ethylene/vinyl acetate/N-vinylpyrrolidone terpolymer.

9. A mineral oil or mineral oil distillate of improved flow behaviour, which contains 0.005 to 0.5 by weight of a mixture of an ethylene/vinyl acetate copolymer and an ethylene/vinyl acetate/N-vinylpyrrolidone terpolyrer. DATED this 24th day of March, 1992. HOECHST AKTIENGESEL LSCHAFT 4 0 4 a o e 4 0 .444 4o 4u WATERMARK PATENT TRADEMARK ATTORNEYS THE ATRIUM 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA DBM:KJS:JZ -1